1. Field of the Invention
This invention relates to selecting one or more visual images from a collection of visual images and, in particular, to selecting one or more visual images from a collection of visual images based on an evaluation of the quality of the visual images in the collection.
2. Related Art
It can be desirable to select one or more visual images from a collection of visual images. The selected visual image(s) can then be extracted from the collection of visual images and presented separately from the collection. For example, it may be desired to select one or more visual images from a visual recording (i.e., one or more series of visual images, each series of visual images acquired at a regular interval by a visual data acquisition apparatus such as a video camera and representing visual content that occurs over a period of time) so that the selected visual image(s) can be extracted and presented as a set of still visual image(s).
A visual image can be manually selected from a collection of visual images, i.e., a human views the visual images in the collection one by one and selects visual image(s) from the collection of visual images. However, manual selection of visual image(s) from a collection of visual images may be undesirably subjective. Further, even if the selection criteria used remain constant, the selection of visual images by a person may be executed inconsistently from visual image to visual image. Additionally, manual selection of visual image(s) from a collection of visual images may be undesirably tedious and cumbersome (and may be impractical), particularly when the collection of visual images is large (e.g., a videotape may include several hundred thousand images).
Visual images can be automatically selected from a collection of visual images. For example, visual images can be automatically selected from a collection of visual images by selecting visual images at regular intervals in the collection of visual images. For instance, visual images can be selected from a visual recording at regular time intervals (i.e., select an image every n seconds) or at regular image intervals (i.e., select every nth image). However, this “mechanical” approach does not take into consideration the characteristics of the visual images, either individually or as a collection, in selecting visual images from a collection of visual images. In some situations in which it is desired to select visual image(s) from a collection of visual images, it can be desirable to consider the characteristics of the visual images and/or the collection of visual images in deciding which visual images to select.
For example, the content of a visual recording can be evaluated to identify segments of visual images containing related content (e.g., scenes can be identified in the visual recording). In such case it is often desirable to identify a visual image (a “keyframe”) to represent each visual recording segment. The set of keyframes are based on the content of the visual recording because each keyframe represents a scene, which is identified based on the visual recording content.
Keyframes can be selected based on a specified relationship to the corresponding scenes. For example, keyframes can be selected based on a specified relationship to other images in the scene (e.g., each keyframe is the nth image from the beginning or end of a scene, such as the first or last image of a scene). Or, for example, keyframes can be selected based on a specified temporal relationship to the scene (e.g., each keyframe is the image that occurs a specified time from the beginning or end of a scene).
Keyframes can also be selected based on an evaluation of the content of the visual images of a scene to identify a visual image that “best” represents the content of the scene. Selection of keyframes in this manner is described in, for example, commonly owned, co-pending U.S. patent application Ser. No. 09/792,280, entitled “Video Processing System Including Advanced Scene Break Detection Methods for Fades, Dissolves and Flashes,” filed on Feb. 23, 2001, by Michele Covell et al., the disclosure of which is hereby incorporated by reference herein.